MS amplifier FET bolts

KUB3 · Post by **KUB3** » Sun Nov 29, 2009 6:34 am

You know the small bare metal hex bolts that hold the FET's in place on MS amps...

Does anyone know if these are imperial or metric? Or even their correct name / size?

Just a shot in the dark, before I go hunting for different types to try... Thanks

Post by **joerg** » Sun Nov 29, 2009 7:32 am

KUB3 wrote:You know the small bare metal hex bolts that hold the FET's in place on MS amps...

Does anyone know if these are imperial or metric? Or even their correct name / size?

Just a shot in the dark, before I go hunting for different types to try... Thanks

Al those screws are imperial! I got a ton of them here from amps i parted out. Just let me know for what amp u need em!

Thunderdome · Post by **Thunderdome** » Sun Nov 29, 2009 7:36 am

yes Jeorgs right they are #4-40 x3/4 long

KUB3 · Post by **KUB3** » Sun Nov 29, 2009 7:44 am

Thanks kindly!

However I had a little plan to swap them to those sexy black allen hex types, as used in Brax:

marko · Post by **marko** » Sun Nov 29, 2009 7:58 am

make sure you use the OEM washers though as they are special ones that are sprung loaded..

KUB3 · Post by **KUB3** » Sun Nov 29, 2009 8:18 am

Yes I remember those. I have all the right bits coming my way - paste, sil pads, etc.

marko · Post by **marko** » Sun Nov 29, 2009 8:23 am

i could use some paste/sil pads just in case, might take a look over on ebay

KUB3 · Post by **KUB3** » Sun Nov 29, 2009 8:27 am

This is how I did mine last time too. RS sell all the right bits.

Post by **Eric D** » Sun Nov 29, 2009 9:34 am

I use 4-40 stainless steel Allen head cap screws. There are at least 3 different lengths inside a MS amp, maybe as much as 5 in all.

KUB3 · Post by **KUB3** » Sun Nov 29, 2009 9:37 am

That looks very good.

I will have to see what the lengths are inside my batch of 275's when I strip them down. I can easily shorten the bolts from stock if required.

marko · Post by **marko** » Sun Nov 29, 2009 9:41 am

Eric that fire engine red amp looks sick

so clean in design and the fet clamps just finish it off

oldschoolfan · Post by **oldschoolfan** » Sun Nov 29, 2009 10:37 am

That red is Smashing!

Pedi · Post by **Pedi** » Sun Nov 29, 2009 11:39 am

Can't agree more guys!! I can't wait to see the Firefighter amp installed, it is soooo good-lookin'......

Eric did a wonderful job on this amp...

KUB3 · Post by **KUB3** » Tue Jan 19, 2010 3:04 am

Thunderdome wrote:4-40

Eric D wrote:4-40

My 4-40 bolts finally arrived after a few weeks and not insignificant cost. Unfortunately 4-40 bolts a freaking HUGE! The thread is three times too thick.

oldschoolfan · Post by **oldschoolfan** » Tue Jan 19, 2010 6:14 am

Did you get 4mm? Or did they send you the wrong bolts? I will also agree they are SAE 4-40.

KUB3 · Post by **KUB3** » Tue Jan 19, 2010 6:23 am

They appear to be over 5mm wide on the thread. No idea what's going on but I have asked for a refund!

Post by **mhyde71** » Tue Jan 19, 2010 10:35 am

yeah- i use sae 4-40 bolts and they work just fine....

@ Eric - did you use stainless washers as well?>?
I am thinking that given the clamp bars being used versus the bolt through the device- that the spring loaded washers are not neccessary- would you tend to agree?

matt

Post by **Eric D** » Tue Jan 19, 2010 11:22 am

I use 4-40 stainless screws, and stainless flat washers. The washers I use are not beveled like the originals, so they don't act as a spring like the originals do. I have never had a problem with this in any amp so far.

The clamp bars don't have beveled washers from PG. The foam on them does the same job keeping pressure on the devices.

I have worked on amps which came back directly from PG having work done on them there. In many of these amps the beveled washers were even installed backwards in places. When installed like this they don't do their job correctly. But, these amps still did not fail this way. I don't therefore don't think the washers are as critical as they may seem.

MS amplifier FET bolts

MS amplifier FET bolts

Re: MS amplifier FET bolts